Store solution and use as a boundary condition for the next run

Hi

Does anybody knows how to apply the results obtained at the outlet of first run back to the inlet as an inlet bounrady condition? Actually the objective is to study a flow in a long clyinder by making it in small cylinders and repeating the BCs from solution back to the inlet. This will save the memory and help in reducing the size of geometry while getting the same results which would actually be obtained in a long clyinder simulation.

Any ideas will be highly appreciated.

regards
Naveed